Lecture Notes Flashcards
Pyroxene Formula
XYSi2O6
X=larger cation Na, Ca, Mn, Fe, Mg, Li
and Y=smaller cation Mn, Fe, Mg, Al
What is the cathode in x-ray diffraction
Tungsten fillament.
It is heated, and it lightens up from electron being emitted.
Constructive vs. destructive interference
Constructive is when 2 waves are n’sync with one another and combine and the aptitude is magnified. Destructive is when 2 waves are combined and their amplitude is dampened.
Debye-Scherger Method
Grind up the unknown mineral. Put specimen in capillary tube, many grains. *randomize the grains. Shoot x-rays at it pew-pew-pew
Phyllosilicates
Sheet Silicates
Si2O5
Platy, flaky, soft, flexible, and elastic.
orthosilicates
Compounds with isolated SiO4 tetrahedra (no sharing of tetrahedral corners with other tetrahedra)
Shielding
If you have a charge on a cation and they are sitting near each other with an oxygen in between they don’t see each other -A matter of relative stability
Shared edges are always _______.
Unshared edges are always _______.
short/long
If the site energy is different what can you expect to happen?
cations to separate
note this doesn’t happen in Olivine
If you increase pressure you will _________ density.
increase. A higher pressure phase will tend to have an atomic arrangement with atoms closer together
As you increase temperature you will ________ density.
Decrease. A higher temperature phase will tend to have an atomic arrangement with atoms further apart.
Something you can use to recreate past temperatures.
geothermometer
Something you can use to recreate past pressures
geobarometer
planes
single sets of atoms arranged in two dimensions.
tetrahedral sheet
corner sharing tetrahedra
octahedral sheet
edge sharing tetrahedra. 2 types trioctahedral (all 3 cations present) dioctahedral sheet (2 of the 3 cations are present)
Layer
A composite of sheets
1:1 layer
One tetrahedra sheet plus one octahedral sheet
2:1 layer
two tetrahedral plus one octahedral sheet
6 varieties of layer silicates
Talc, Mica, Smectite, chlorite, 1:1, 2:1
which expands more smectite or vermiculite?
smectite
polytypism
A special type of polymorphism due to stacking in one direction
Polytypes
To specify the structure.
Tetrahedral/octahedral sheet misfit-increase the tetrahedral sheet
requires that the tetrahedral out of the plane tilts.
Clay
A general term for fine grained material. Generally plastic with a limited amount of water and it will harden when dried or fired. Exact size requirements vary by discipline.
How does a clay structure look if salt is not present?
Builds up like a stack of cards. Colloid framework.
How does a clay look if salt is present?
Everything collapses “flocculation”
Economic Importance of zeolites
molecular, drying, catalyst, exchange reactions
